The Contribution of cocoa additive to cigarette smoking addiction

Page 6 of 207 RIVM report 650270002
1. Introduction
Cigarette smoking is an easy way to administer multiple doses of the psychoactive drug
nicotine. However, it leads to nicotine addiction and it is the most important cause of
preventable death (1). Hence, prevention and quitting smoking are major public health goals.
It has been suggested that cigarette smoking is more addictive than nicotine alone due to the
fact that tobacco or smoke seems to contain compounds which increase the addictive potency
of nicotine (e.g. ammonium compounds) (2) or may be addictive in their own right (e.g.
cocoa) (3, 4).
Craving for chocolate, which contains cocoa, is a well-known phenomenon and to emphasize
its addictive properties the term “chocoholics” is used for individuals who report overeating
chocolate. However, whether cocoa has addictive properties, remains debatable. There has
been speculation that chocolate craving is related to organoleptic properties of chocolate and
probably to rewarding effects of psychoactive compounds in chocolate. The organoleptic
properties of chocolate improve the mood, leading to an increase in pleasant feeling and a
reduction of tension. Chocolate is generally rated as highly palatable, which is attributed by
high levels of carbohydrate and fat. The sensory characteristics and the palatability of
chocolate attribute the organoleptic properties. However, there are other foods, which have
similar palatable properties as chocolate, but are less craving (4). Michener and Rozin (1994)
(5) suggested that sensory experience at one hand and palatability at the other hand satisfy
chocolate cravings. There is no convincing evidence that eating chocolate leads to physical
dependence to one or more of the psychoactive compounds it contains. The recent discovery
of endocannabinoids in cocoa (6) suggested that psychoactive compounds in chocolate might
attribute to chocolate craving. However, it seems that the level of the psychoactive
compounds in chocolate is too small to elicit chocolate dependency (7).
Cocoa is used at a level between 1 % (w/w) and 3 % (w/w) in the casing of tobacco products
as a flavour enhancer (8, 9). The suggestion that chocolate may have addictive properties was
extrapolated to the addictive properties of cocoa as an additive in tobacco products (9, 10). It
is speculated (9, 10) that cocoa added to tobacco increases the addictive properties of
cigarettes by the action of psychoactive compounds in cocoa. Although there is no indication
that eating chocolate leads to dependency on the psychoactive compounds, some distinction
has to be made to the addictive qualities between oral exposure to cocoa by eating chocolate
and pulmonary exposure to cocoa by smoking cigarettes. Firstly, the different exposure route
of cocoa may have different pharmacological effects on the body. The psychoactive
compounds may exert a local pulmonary effect, thereby affecting the nicotine availability. In
this case, it is argued (9, 10) that cocoa compounds, such as theobromine, may have
bronchodilating effects, thereby increasing the level of nicotine absorption. Furthermore, by
exposing through the pulmonary system, the rapid degradation of the psychoactive
compounds by the liver is avoided. Secondly, the psychoactive compounds are combusted
during smoking and reaction products of these compounds with other compounds are formed.
These reaction products may affect the addictive properties of cigarettes.
So far, the effect of cocoa on the addictive properties of tobacco products has not been
investigated. In this study ten psychoactive compounds of cocoa are reviewed: theobromine,
caffeine, serotonin, histamine, phenylethylamine, tryptamine, tyramine, tryptophan,
octopamine and anandamide. These compounds are reviewed by their chemical,
environmental and smoking exposure, pharmacological, pharmacokinetic, toxicological,
interaction and dependency properties. These properties are discussed in relation to the
pulmonary exposure by smoking cigarettes.